A known composite cable is disclosed in U.S. Pat. No. 5,544,270 wherein a cable is described having multiple twisted pairs of electrical conductors in combination with optical fiber conductors. The known cable has interstices between the twisted pair conductors and optical fiber conductors, none of which interstices include water blocking features. Water blocking is important because it prevents the cable from becoming a conduit for the flow of water. Moreover, the optical fiber conductors are not protected by strength members.
A second known composite cable is disclosed in U.S. Pat. No. 5,539,851, which cable includes a single central, tight buffered optical fiber surrounded by a ring of electrical conductors and a braided sheath RFI shield. The optical fiber is immediately surrounded by a KEVLAR sleeve and a TEFLON jacket. Because the composite cable has a single fiber, it has limited information carrying capacity. Additionally, the composite cable does not provide water blocking features in the interstices adjacent the electrical conductors. Moreover, the combination of a KEVLAR sleeve, TEFLON jacket, a ring of electrical conductors, and a braided sheath results in a large, stiff composite cable which is not particularly suited to being routed through cable enclosures.
A third known composite cable is disclosed in U.S. Pat. No. 5,481,635, which cable includes a single large, central broadband coaxial cable, a set of voice-line twisted pair conductors, and a set of power conductors disposed around the coaxial conductor. Water blocking members are disposed about the coaxial cable. Compared to a fiber optic core, however, a coaxial core is disadvantageous because it has a smaller bandwidth, and is subject to higher power loss. Moreover, the coaxial conductor is subject to electormagnetic interference, impedance, and electrical cross talk. Further, the coaxial conductor core is generally relatively heavier and larger making it harder to install than an optical fiber core. Additionally, the coaxial conductor presents a spark hazard. Finally, because the coaxial conductor emits electromagnetic energy, it is easier to tap and is therefore less secure than an optical fiber core.